Drycleaner Site Profiles

Varsity Cleaners, Temple Terrace, Florida

Description
Historical activity that resulted in contamination.

Drycleaning using PCE, was conducted in a stand-alone building at this site from the mid-1960s until 1998. The building housing the drycleaning operation was previously occupied by an auto service center. In 1998, Varsity Cleaners moved to a new building located on an adjacent property. The site is located in a mixed commercial/residential setting. A service station with associated petroleum contamination was formerly located on an adjacent property. The nearest water supply well is located one-half mile northeast of the site. The contaminant source areas identified at the facility were the soils beneath the building floor slab near the drycleaning machine, the area near the service door, and a concrete vault located beneath the facility floor slab that received wastewater.

Remediation Status: In groundwater monitoring


Contaminants
Contaminants present and the highest amount detected in both soil and groundwater.


Contaminant Media Concentration (ppb) Nondetect
Tetrachloroethene (PCE) groundwater 4,940 ppb
Tetrachloroethene (PCE) soil 2,260 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   45ft bgs
Plume Size:   Plume Length: 420ft
Plume Width: 300ft
Plume Thickness: 25ft
Average Depth to Groundwater:   20ft

Lithology and Subsurface Geology

 
  fine-grained sand
Depth: 0-22ft bgs
22ft thick
Conductivity: 2.9ft/day
Gradient: 0.008ft/ft
 
  clay
Depth: 22-28ft bgs
6ft thick
 
  sandy clay, clay and weathered limestone
Depth: 28-50ft bgs
22ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkDNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
 
Has a vapor mitigation system been installed?
  Yes 
Type of Vapor Mitigation System(s):
  Soil Vapor Extraction

Remediation Scenario

Cleanup Goals:
  Groundwater - PCE = 3.0 µg/L; TCE = 3.0 µg/L; cis 1,2-DCE = 70 µg/L.

Soil - leachability standard - PCE = 30 µg/kg, TCE = 30 µg/kg, cis 1,2-DCE = 40 µg/kg
Remedy Level:
  Full Scale Remedy

Technologies

In Situ Bioremediation
 

Why the technology was selected:
Bioremediation was selected as a final active groundwater remedy to polish the remaining groundwater contamination that the pump & treat system had failed to remove. The pilot study objective was to determine if an anaerobic enviornment could be created to degrade the PCE to daughter products that would be degraded into innocuous products when they migrated into the aerobic portion of the aquifer.

Date implemented:
September 14 - November 5, 1998: Excavtion & onsite treatment of contaminated soil. December 8, 1999: Pump & treat system begins operation. May 2004: Enhanced bioremediation inititated.

Final remediation design:
The bioremediation system utilized recovered groundwater that was treated and then mixed with potassium lactate. The potassium lactate/groundwater solution was re-injected via the recovery trench system in order to create anaerobic conditions and degradet the contaminants via reductive dechlorination.

Results to date:
Enhanced bioremediation was conducted at the site from May 2004 until December 2007. Durng that time twelve (12) injection events of 60% potassium lactate solution were conducted. Potassium lactate injection volumes ranged from three (3) to twenty-four (24) gallons. Total potassium lactate injection volume for the project was 139 gallons. An estimated 90,000 gallons of groundwater was extracted, treated and re-injected during this period. The groundwater extraction system ran at an average rate of 0.97 gpm. Potassium lactate injection resulted in the the creation of PCE daughter products TCE, Cis 1,2-DCE and Trans 1,2-DCE in groundwater in the treatment area. Contaminants were not detected in concentrations exceeding cleanup target levels in groundwater samples collected during the last five consecutive groundwater monitoring events (February and July of 2007, January and March of 2008 and in January of 2009.

Next Steps:
A Site Rehabilitation Completion Order was issued for this site on August 7, 2009.

Cost to Design and Implement:
Soil excavation & treatment; 350,000 Other remedial efforts: 243,200

Ex Situ Carbon Adsorption
 

Why the technology was selected:
Pump & treat was initially selected to remediate contaminated groundwater at the site because the contaminant source area was small in size and a well vault had been installed during the excavation. The pump & treat system had a dual purpose: recover and treat contaminated groundwater and provide hydraulic containment of the contaminant plume.

Date implemented:
September 14 - November 5, 1998: Excavtion & onsite treatment of contaminated soil. December 8, 1999: Pump & treat system begins operation. May 2004: Enhanced bioremediation inititated.

Final remediation design:
A groundwater recovery system was installed via trench box (6 ft x 20 ft x 14 ft) at the base of the excavation to a total depth of 34 ft bgs into the top of a weathered limestone. Three sets of 20-foot horizontal 6-inch diameter perforated PVC pipes were installed in the trench box at depth of 34, 24 and 18 ft bgs. Both ends of the pipes were fitted with 6-inch risers and backfilled. The trench box was then lined with geotextile fabric and backfilled with #57 stone. The excavtion was then backfilled with treated soil. The pump and treat system consists of a Grunfos 5E5 submersible pump with a design flow rate of 4-5 gpm. The system was operated only during the wet season. Extracted water is treated with two 200-lb. liquid G.A.C. units. Design operating flow rate for the pump & treat system was 1.5 gpm. Treated groundwater was discharged to an infiltration gallery.

Next Steps:
A Site Rehabilitation Completion Order was issued for this site on August 7, 2009.

Cost to Design and Implement:
Soil excavation & treatment; 350,000 Other remedial efforts: 243,200

Ex Situ Pump and Treat
 

Why the technology was selected:
Pump & treat was initially selected to remediate contaminated groundwater at the site because the contaminant source area was small in size and a well vault had been installed during the excavation. The pump & treat system had a dual purpose: recover and treat contaminated groundwater and provide hydraulic containment of the contaminant plume.

Date implemented:
September 14 - November 5, 1998: Excavtion & onsite treatment of contaminated soil. December 8, 1999: Pump & treat system begins operation. May 2004: Enhanced bioremediation inititated.

Final remediation design:
A groundwater recovery system was installed via trench box (6 ft x 20 ft x 14 ft) at the base of the excavation to a total depth of 34 ft bgs into the top of a weathered limestone. Three sets of 20-foot horizontal 6-inch diameter perforated PVC pipes were installed in the trench box at depth of 34, 24 and 18 ft bgs. Both ends of the pipes were fitted with 6-inch risers and backfilled. The trench box was then lined with geotextile fabric and backfilled with #57 stone. The excavtion was then backfilled with treated soil. The pump and treat system consists of a Grunfos 5E5 submersible pump with a design flow rate of 4-5 gpm. The system was operated only during the wet season. Extracted water is treated with two 200-lb. liquid G.A.C. units. Design operating flow rate for the pump & treat system was 1.5 gpm. Treated groundwater was discharged to an infiltration gallery.

Results to date:
The pump & treat system operated intermittently (during the wet season) from December 8, 1999 to November 7, 2002. Total operation time during that period was approximately 18.5 months. Average pumping rate was 0.93 gpm. The highest contaminant influent concentration detected was 660 ug/l PCE. The sytem recovered and treated over 600,000 gallons of contaminated groundwater. Operating flow rate for the pump & treat system is approximately 1.5 gpm. The system is operated only during the wet season. Initial influent concentrations for the pump & treat system were as high as 660 µg/L PCE. During the latest operation period, influent concentrations were as high as 440 µg/L PCE. Through December 2, 2001, a total of 392,381 gallons of water had been treated by the system. Contaminants were not detected in concentrations exceeding cleanup target levels in groundwater samples collected during the last five consecutive groundwater monitoring events (February and July of 2007, January and March of 2008 and in January of 2009.

Next Steps:
A Site Rehabilitation Completion Order was issued for this site on August 7, 2009.

Cost to Design and Implement:
Soil excavation & treatment; 350,000 Other remedial efforts: 243,200

Ex Situ Soil Removal
 

Why the technology was selected:
Excavation was selected over soil vapor extraction because the building that housed the drycleaning operation had been razed and the contaminated soil was accessible to excvation.

Date implemented:
September 14 - November 5, 1998: Excavtion & onsite treatment of contaminated soil. December 8, 1999: Pump & treat system begins operation. May 2004: Enhanced bioremediation inititated.

Final remediation design:
Soil Excavation & Treatment: Sheet piling was utilized to stablize the northern boundary of the property. A total of 3,250 cubic yards of soil was excavated ( 30 ft x 30 ft x 20 ft bgs) with a 2:2 slope - total excavated area 70 ft x 110 ft. Soil with detectable levels of PCE was stockpiled in a bermed area with a leachate collection system. Parallel 4-inch screened PVC pipes were installed horizontally, 1 foot from the bottom of the treatment pile with valves installed on both ends of the piping to allow vacuum or a passive vent to the atmospher to be applied to the soil pile. SVE pipes were then alternated between passive air, air recovery, and air injection points. Two 4-inch diameter pipes were installed along the length of the pile 5 feet from the bottom of the pile. The treatment pile continaed approxiamtley 1,750 cubic yards of soil (108 ft x 40 ft x 8 ft). The pile was covered with visqueen to prevent short circuiting frm teh atmosphere. Longitudinal piping was used for air input and the transverse pipes were used for air recovery. During the treatment period, air input and recovery pies were alternated. Recovered leachate was treated using air strippers and then discharged to an exfiltration gallery.

Results to date:
Excavation began 9/14/98. Onsite soil treatment 9/30/98 to 11/5/98.

Next Steps:
A Site Rehabilitation Completion Order was issued for this site on August 7, 2009.

Cost to Design and Implement:
Soil excavation & treatment; 350,000 Other remedial efforts: 243,200

Costs

Cost for Assessment:
  $148,300 soil
Cost for Operation and Maintenance:
  O&M (includes monitoring): 27,200 Restore site: 11,700
Total Costs for Cleanup:
  780,400

Lessons Learned

1. If an excavation had not been conducted, the underground vault would not have been discovered and would have been an ongoing contaminant source. The vault received laundry wastewater and contact water from the drycleaning operation.

2. The clay and weathered limestone at the site contain residual sorbed contaminants that were addressed in part by the pump & treat system, but the removal of contaminated soils at the site resulted in a significant decrease in contaminant concentrations in groundwater.

3. Some of the problems in operating the enhanced bioremediation system were the return to aerobic conditions during the seasonal drop in the water table and the difficulty of recoverying sufficient groundwater to mix with potassium lactate during periods of low water tables. Another problem that occurred was biofouling of the G.A.C. treatment unit.

Contacts

Stacie Davis, Project Manger
Bureau of Waste Cleanup
Florida Department of Environmental Protection
2600 Blair Stone Road, Mail Station 4520
Tallahassee, Fl. 32399-2400
850-245-8967
Anastasia.Davis@DEP.state.fl.us

Contractor:
Brian Moore
H.S.A. Environmental Engineers & Scientists
4019 East Fowler Ave.
Tampa, Fl. 33167
850-971-3882
bmoore@hsa-env.com

Site Specific References

Site Assessment Report - June, 1998

Interim Source Removal Report: June 2002

Bioremediation Pilot Study: September 2004.

Operation & Maintenance/Monitoring Reports: 200 - 2008.